There is need for a miniature, non-gravity-dependent infusion device that is sufficiently small and light to be used as a wearable unit. One important application for a wearable infusion device is for total parenteral nutrition. The availability of a reliable, wearable infusion device could free patients for varying periods of time from attachment to existing, bulky infusion pumps and improve the quality of life. Other applications for a wearable infusion device could be for enteral feeding, continuous drug infusion, chemotherapy for cancer patients and continuous delivery of insulin to diabetics. A small non-gravity-dependent infusion device could also be valuable for patient transport and for ordinary intravenous infusion procedures. The proposed approach is twofold, providing: a container for the IV fluid in which the fluid can be pressurized through a flexible barrier, and which can be oriented in any position; and means to pressurize the IV fluid within the container by air to maintain a constant flow rate of IV fluid. Advantages are that a standard IV infusion set is used; the flow rate is independent of the container position; and the pumping device is small, light and feasible for a wearable unit.